Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, China.
Department of Life Science, Hiroshima Institute of Technology, Hiroshima, Japan.
PLoS One. 2020 May 12;15(5):e0232927. doi: 10.1371/journal.pone.0232927. eCollection 2020.
Tetraene macrolides remain one of the most reliable fungicidal agents as resistance of fungal pathogens to these antibiotics is relatively rare. The modes of action and biosynthesis of polyene macrolides had been the focus of research over the past few years. However, few studies have been carried out on the overproduction of polyene macrolides. In the present study, cumulative drug-resistance mutation was used to obtain a quintuple mutant G5-59 with huge tetraene macrolide overproduction from the starting strain Streptomyces diastatochromogenes 1628. Through DNA sequence analysis, the mutation points in the genes of rsmG, rpsL and rpoB were identified. Additionally, the growth characteristic and expression level of tetrRI gene (belonging to the large ATP binding regulator of LuxR family) involved in the biosynthesis of tetraene macrolides were analyzed. As examined with 5L fermentor, the quintuple mutant G5-59 grew very well and the maximum productivity of tetramycin A, tetramycin P and tetrin B was as high as 1735, 2811 and 1500 mg/L, which was 8.7-, 16- and 25-fold higher than that of the wild-type strain 1628, respectively. The quintuple mutant G5-59 could be useful for further improvement of tetraene macrolides production at industrial level.
四烯大环内酯仍然是最可靠的杀真菌剂之一，因为真菌病原体对这些抗生素的耐药性相对较少。多烯大环内酯的作用方式和生物合成一直是过去几年研究的重点。然而，关于多烯大环内酯的过度生产的研究很少。在本研究中，采用累积耐药突变的方法，从出发菌株绛红链霉菌 1628 中获得了一个具有巨大四烯大环内酯过度生产能力的五重突变体 G5-59。通过 DNA 序列分析，确定了 rsmG、rpsL 和 rpoB 基因中的突变点。此外，还分析了参与四烯大环内酯生物合成的 tetrRI 基因（属于 LuxR 家族的大型 ATP 结合调节子）的生长特性和表达水平。在 5L 发酵罐中进行检查时，五重突变体 G5-59 生长良好，四霉素 A、四霉素 P 和四林 B 的最大产量高达 1735、2811 和 1500mg/L，分别比出发菌株 1628 高 8.7 倍、16 倍和 25 倍。五重突变体 G5-59 可用于进一步提高工业水平的四烯大环内酯的生产。
